O’Callaghan said: “I leave the game with a profound sense of gratitude for all that it’s given me. Physically I feel I can go on but now is the right time to go.

“It’s time to spend more time with the kids. A professional sportsman has to lead a selfish life, but it’s not fair on my family any more for me to keep doing this while precious time ebbs away with me in one country and my family in another.

“There are a lot of people to thank for my time in the game, during which I have also made so many wonderful lifelong friends, and to each and every one of you, I’d like to say a very big thank you.

“I’d like to thank Worcester in particular for making me feel so welcome and treating me so well. I’ve certainly felt at home for the past three seasons and I wish the Club the best of luck in the future.”

O’Callaghan amassed 98 Test caps, with 94 for Ireland and four for the British & Irish Lions, while he also represented the illustrious Barbarians on two occasions.

He captained the Lions in South Africa in 2009 and featured in three consecutive World Cups for Ireland between 2003 and 2011, and won the Six Nations Grand Slam in 2009.

O’Callaghan also had a decorated 17-year spell with hometown club Munster Rugby, where he won two Heineken Cup titles and two Magners League titles in his 268 appearances.